The present invention relates generally to electric motor drive mechanisms and more particularly to the structure and arrangement of a motor drive unit particularly suitable for washing machines. More specifically, the invention relates to a drive assembly utilizing an electric motor wound to effect operation with a differing number of poles with the driven member of the assembly being driven at high speed operation through a centrifugal frictional clutch directly engaging between the driven member and the motor shaft or at low speed operation through planetary gearing driven by the motor shaft and connected to transmit power to the driven member through an overrunning clutch and a hollow shaft rotatably fixedly engaged on the driven member, with the overrunning clutch disengaging when the hollow shaft exceeds a predetermined speed as a result of driving engagement of the driven member with the motor shaft through the centrifugal frictional clutch.
A drive for washing machines of the type to which the present invention relates is known from German Offenlegungsschrift No. 22 54 745. In this known drive arrangement, the motor shaft is supported on both sides of the motor armature immediately in a roller bearing in each motor housing flange. A one-piece motor shaft projects beyond one of the motor housing flanges to an extent such that a planetary gearing, an overruning clutch, a driven member which is usually constructed as a belt pulley and a centrifugal frictional clutch can be accommodated in the axial direction of the assembly adjacent each other on the motor shaft. Accordingly, the motor shaft must be dimensioned with sufficient thickness so that radial forces occurring at the driven member can be absorbed by the motor shaft to accommodate for its relatively long unsupported length. Moreover, the large diameter of the motor shaft necessitates large dimensions for the bearings and the planetary gearing thereby increasing all of the dimensions of the washing machine drive unit to an undesirable degree thereby increasing the expense of the washing machine drive.
Accordingly, the present invention is directed toward the task of providing techniques whereby the dimensions of the drive unit of a washing machine of the type in question may be reduced. More particularly, the invention seeks to reduce the dimensions of the motor drive shaft of the drive unit while at the same time providing a unit which is simple to assemble and wherein the centering of the planetary gearing is especially relatively simple to accomplish.